The Lunar Nodal Cycle influence on the Arctic Climate

The Arctic Ocean is a substantial energy sink for the Earth’s Northern Hemisphere. Fluctuations in its energy budget will have a major influence on the Arctic climate. This paper presents an analysis of the time series for the polar position, the extent of Arctic ice, the sea level at Hammerfest, the Kola section sea temperature, the Røst air winter temperature and the NAO winter index as a way to identify a source of dominant cycles. The investigation uses a wavelet transform to identify the time and phase of dominant cycles in these Arctic time series. The system dynamics is identified by studying of the phase-relation between the dominant cycles in all time series. The investigation has identified a harmonic spectrum from the 18.6-year lunar nodal cycle in the Arctic time series. The cycles in this harmonic spectrum have a stationary cycle time, but not a stationary amplitude and phase. A sub-harmonic cycle of about 74 years may introduce a phase-reversal of the 18.6-year cycle. The signal- to noise-ratio between the lunar nodal spectrum and other sources changes from 1.6 to 3.2. A lunar nodal cycle in all time series indicates that there is a forced Arctic oscillating system controlled by the pull of gravity from the moon. This Arctic oscillation system influences long-term fluctuations in the extent of Arctic ice. The lunar nodal spectrum of Arctic ice extent influences the NAO winter index, the weather and the climate.